Decreased number of locules and pericarp cell layers underlie smaller and ovoid fruit in tomato smaller fruit (sf) mutant

Fruit size and shape are the prime criteria for domestication and improvement of tomato. The varying sizes and shapes of tomato fruits further signify their importance as agronomic traits. Here, we characterized a tomato mutant, smaller fruit (sf), which bears relatively small and ovoid fruits compared with large and flat fruits of wild-type (WT). Phenotypic measurements and histological analyses revealed that fruit diameter but not fruit length of sf mutant decreased compared with that of WT. This phenotypic change was attributed to significant decreases in locule number and pericarp cell layers in transverse direction, which resulted in the transition of fruit shape from flat in WT to ovoid in sf. Comparison of transcriptomes of ovaries between sf and WT by RNA-Seq identified 2,596 differentially expressed genes, in which 1,737 genes significantly up-regulated and 859 genes dramatically down-regulated in the sf ovary. Further analyses confirmed that some genes, such as CRCa, CNRs, CYCs, WUS, SUNs, OFRs, CDKs, participate in regulation of fruit size and shape of sf mutant. Thus, our study adds a new genetic resource regarding fruit size and shape of tomato, and provides a valuable basis for dissecting molecular regulation of small and ovoid fruit of sf mutant.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author